Soldering solution



Patented May 17, 1938 SOLDERING SOLUTION Clete L. Boyle, Detroit, Mich.

No Drawing.

Application April 1, 1936,

Serial No. 72,060

1 Claim.

This invention relates to an improved soldering flux. The present application forms a continuation-in-part of my earlier filed application Serial No. 717,266, filed March 24, 1934.

Soldering solutions commonly comprise water solutions of a fluxing agent such as zinc chloride and a. small percentage of ammonium chloride, a rust attacking and removing acid such as muriatic acid and an oil and grease solvent such as butyl alcohol, butyl acetate, ethyl methyl ketone.

A solvent which I have found to have particularly desirable properties is mono butyl ether of ethylene or di-ethylene glycol. The ether derivatives of ethylene or di-ethylene glycol possess high solvent properties, a low evaporation rate, are only remotely inflammable and are readily miscible in water in substantially all proportions.

Due to the smallness of the crevices and the peculiar irregularities of the metal surfaces upon which the soldering solution is used it is highly desirable that the solution employed be one that will thoroughly wet and completely spread over metal surfaces to be treated. A commercial use in question is in the fabrication of sheet metal automobile bodies. The solution should be capable of spreading and creeping into the crevices and joints thoroughly wetting the surfaces and it should remove the rust, oil and grease so that the fluxing action may be uniformly and properly carried out.

To facilitate the wetting of the surface of the metal a wetting agent may be employed as one of the ingredients in the solution. This wetting agent should so function in the solution that after the metal surface has been properly wetted the oil solvent in the solution will have free play to act upon the oil and grease film and the muriatic acid will be unrestricted to act freely to remove the rust and the scale and the fluxing action will proceed properly. a

Generally speaking there are hundreds of different wetting agents but while certain ones are highly satisfactory in one environment they are wholly unsatisfactory for use in other environ- 45 ments. In ordinary laundry procedure soap is the usual wetting agent. Soap functions satisfactorily in a. neutral or alkaline solution but is unsuitable as a wetting agent in an acid soldering flux solution because of the tendency of the soap to break down with the resulting liberation of the fatty acids therein.

Sulphonated mineral oils include many well known wetting agents but generally these do not form true chemical solutions in soldering flux solutions and are not properly compatible with the other ingredients used therein. Mineral oils are essentially straight chain hydrocarbons and, whether of the parafiin base or asphalt base type, they resist sulphonation. The mineral oils include as ingredients many hundreds of different organic chemicals, the character and presence of which depend upon the source of the oil but of these numerous ingredients the naphthenic acid ingredients are the only ones that respond to sulphonation. These naphthenic acids are present in mineral oils in very minute quantities varying from .03 to .30 of 1% of the total amount of the oil. In many instances sulphonation results in the formation of mahogany acids as the sulphonated product and these mahogany acids are not water soluble but are soluble in oil only and as such are not usable as wetting agents in aqueous soldering flux solutions.

Sulphonated vegetable oils likewise form a large .class of wetting agents but these form colloidal solutions or emulsions in acid soldering flux solutions and do not form true chemical solutions of the character here set forth. Care must also be used as to the character of the water used in the. solution because if certain hard waters are employed the calcium or magnesium salts are precipitated out, rendering the solution unsatisfactory.

Soldering solutions employing wetting agents, wherein the solution is an emulsion or colloidal solution have heretofore been suggested but the particular soldering solution here described is not of this class. The soldering solution here sought is a true clear chemical solution wherein each of the constituent ingredients is free and unrestricted to perform its intended purpose in the solution; The improved soldering solution here described employs a wetting agent which not only assists to a maximum extent the dispersion of the other ingredients. over the surface of the metal but does not hamper in any way such other ingredients in carrying out their intended function. This improved soldering solution is one wherein the activity and mobility of each component of solution is vastly increased and promoted as compared with the restricted permitted activity of the ingredients in a colloidal solution.

The class of aromatic hydrocarbons contains many which when sulphonated form wetting agents which will form true chemical solutions in an acid environment, but many of them, such as Neomerpin, remain stable only in the presence of weak acids and unfortunately most of these sulphonated aromatic hydrocarbons tend to precipitate metals, and particularly zinc, out of the solution and in doing so the wetting agent itself is thrown out of solution as a complex insoluble precipitate. However it has been found that certain derivatives .f certain nitrogenous hydrocarbons, such as the amino acids of either the aliphatic or the aromatic series, when sulphonated and condensed with alkylating or aralkylating agents, not only form true chemical solutions but serve with unusual effectiveness as wetting agents in acid solutions of either low or high concentration and possess unusually desirable properties as wetting agents in the aqueous acid soldering flux solutions. any tendency to precipitate out the metal such as zinc, etc. The amino acids when treated as herein set forth, appear to possess all those ch'ar acteristics which make for a'successful wetting agent in soldering flux solutions.

A suitable amino acid of the aliphatic series is alanine (alpha-amino-propionic acid,

CHzCH (NH2) COOH) which is sulphonated with oleum (fuming sulphonic acid) to form alpha-amino-propionic sulphonic acid. This product is then condensed with a suitable allwl or aralkyl agent such as benzyl chloride or cetyl chloride to form benzyl or cetylalpha-amino-propionic sulphonic acid. Sulphanilic acid also known as amino benzene sulphonic acid may be similarly sulphonated and alkylated or aralkvlated to form cetyl or benzyl 2.4 aniline di-sulphonic acid, a suitable amino acid wetting agent of the aromatic series.

Wetting agents such as the two above mentioned function in an acid soldering solution whether of weak or strong concentration to cause the rust attacking acid and the oil and grease solvent to spread to a maximum extent over the surface of the metal thoroughly and completely wetting the same. Not only do they produce this result but they do not inhibit in any way the intended action of the rust removing acid or the action of the rust and grease solvent. On the contrary, they appear to emphasize and augment Water ns 10 Zinc chloride 1301111115-- 37 Ammonium chloride do 3 Muriatic acid 18 gallon 1 Mono butyl ether of ethylene glycol do l Wetting agent, such as benzyl-alpha-aminopropionic sulphonic acid or cetyl 2.4-aniline di-sulphonic acid ounces 3 In the above formula thezinc chloride may be replaced with any product having fiuxing They do not possess 'colloidal solution or emulsion.

ability. It has been found that when a nitrogenous fluxingagent such as aniline hydrochloride or acetamide hydrochloride is substituted a smaller proportion of the specific nitrogenous wetting agent is required. The nitrogenous wetting agents specifically cited herein have an unusually desirable afllnity for a nitrogenous fluxing agent because of their like character and make a very effective soldering flux solution. Due to their nitrogenous character they are thoroughly compatible and readily miscible with the other ingredients in the solution which are of a nitrogenous derivation. A representative formula might comprise the following formula:

Water gallons 10 Aniline hydrochloride or acetamide hydrochloride pounds 37 Ammonium chloride do 3 Muriatic acid 18 gallon 1 Mono butyl ether of ethylene glycol do 1 Wetting agent, such as benzyl-alpha-aminopropionic sulphonic acid or cetyl 2.4-aniline di-sulphonic acid ounce 1 These improved fluxes are used in the same manner as ordinary fluxes. It will be found that these new types of fluxes, possessing as they do such improved wetting and spreading ability will reach into the corners and crevices and all irregularities of the surfaces to function in a manner utterly impossible with the regular type of fluxes.

This improved soldering solution is a true, clear, chemical solution as distinguished from a It is stable in acid solutions of widely varying character and strength and does not break down or stratify. It is miscible with water of any character and does not precipitate the calcium or other salts thereof. It does not cause the metals-such as the zinc to precipitate out. It possesses a maximum wetting capacity and increases rather than restricts the intended functioning of the rust attacking acid and the oil solvent ingredients in the solution. It functions compatibly with the nitrogenous fluxing agents specified asv they are of a like character.

What I claim:

A soldering preparation comprising a fiuxing agent, a metal etching acid, mono butyl ether of ethylene glycol, and a wetting agent consisting of cetyl 2.4-aniline di-sulphonic acid.

CLETE L. BOYLE. 

